change order, key -> uid and value -> display name, this way it is also possible to have non-unique display names

first commit with some infrastructure code

add additional mail_smtp.. parameters to fix possible SMTP connection problems.

Fix rendering of database connection error page

Add two specific mimetype extensions (ebooks): for epub and mobi files

fixed an other typo.

Fixed type in line 70. Thank you for pointing me to that typo.

Remove unnecessary ob_end_clean() from template tests

Files encryption

Conflicts:
	apps/files_encryption/templates/settings.php

Added three additional mail_smtp.. parameters.
- mail_smtpdebug - enable debug messages to analyse SMTP problems.
- mail_smtptimeout - set SMTP timeout which is set to 10s by
  default and this is sometimes to short especially if a malware/
  spam scanner is used.
- mail_smtpsecure - force secure SMTP connections.

Added three additional mail_smtp.. parameters.
- mail_smtpdebug - enable debug messages to analyse SMTP problems.
- mail_smtptimeout - set SMTP timeout which is set to 10s by
  default and this is sometimes to short especially if a malware/
  spam scanner is used.
- mail_smtpsecure - force secure SMTP connections.

Fix scrolling of leftcontent

cached queries need to be reset on schema change because they become inv...

fixes: https://github.com/owncloud/apps/issues/468